J/A+A/569/A91 Optical imaging for S4G (Knapen+, 2014)
Optical imaging for the Spitzer Survey of Stellar Structure in Galaxies.
Data release and notes on interacting galaxies.
Knapen J.H., Erroz-Ferrer S., Roa J., Bakos J., Cisternas M., Leaman R.,
Szymanek N.
<Astron. Astrophys. 569, A91 (2014)>
=2014A&A...569A..91K 2014A&A...569A..91K
ADC_Keywords: Surveys ; Galaxies, optical
Keywords: galaxies: structure - galaxies: interactions - surveys
Abstract:
The Spitzer Survey for Stellar Structure in Galaxies (S4G) and its
more recently approved extension will lead to a set of 3.6 and 4.5um
images for 2829 galaxies, which can be used to study many different
aspects of the structure and evolution of local galaxies.
We have collected and re-reduced optical images of 1768 of the survey
galaxies, aiming to make these available to the community as
ready-to-use FITS files to be used in conjunction with the mid-IR
images. Our sky-subtraction and mosaicking procedures were optimised
for imaging large galaxies. We also produce false-colour images of
some of these galaxies to be used for illustrative and public outreach
purposes.
We collected and re-processed images in five bands from the Sloan
Digital Sky Survey for 1657 galaxies.
Description:
Details on the optical image release are presented in table1.dat.
These include galaxy names, source of the optical data, available
bands, field of view of the image cutout, and calibration information
(LT data only).
Table 3 contains relevant information on those galaxies with close
companions. We indicate its interacting class (if any), diameter,
systemic velocity, apparent magnitude, separation between companion
galaxies, and optical data source, if available.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 65 1768 Details on optical images
table2.dat 129 587 Properties of galaxies with close companions,
and of interacting galaxies
img/* . 8396 Individual FITS images
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See also:
J/PASP/122/1397 : Spitzer Survey of Stellar Structure in Galaxies (Sheth+ 2014)
J/A+A/562/A121 : ARRAKIS: Atlas of Resonance Rings as Known In S4G
(Comeron+ 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 24 A24 --- Galaxy Common Galaxy Name
27- 33 I07 --- PGC The Catalogue of Principal Galaxies (PGC)
Number
35- 43 A9 --- src Source of the optical images (G1)
46- 54 A9 --- Bands Bands in which optical data is available
56- 60 F5.1 arcmin FOV Size of the image field of view
62- 65 A4 --- Calib Calibration system for the LT data (1)
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Note (1): Details on the flux calibration system as follows:
1 = from standard stars
2 = from g' magnitude (valued from NED)
2.1 = g' computed from B and V
2.2 = g' computed from B and R
2.3 = g' computed from B and I
2.4 = g' computed from B, R and I
2.5 = g' computed from B and J
X = not flux-calibrated
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Galaxy Common S4G galaxy name
47 A1 --- iC [ABC] Interaction class, if any (1)
50- 53 F4.1 arcmin Diam [1/24] Galaxy major diameter
55- 58 I4 km/s Vel Galaxy recession velocity
61- 64 F4.1 mag mag Galaxy optical magnitude
66- 68 A3 --- src Source of optical data, if any (G1)
70- 99 A30 --- Companion Common name of companion galaxy
104-107 I4 km/s Velc Companion recession velocity
110-113 F4.1 mag magc Companion optical magnitude
115-118 F4.1 arcmin Sep1 Separation between galaxies in arcmin
121-123 F3.1 --- Sep2 ?=- Separation, in sample galaxy diameters
125-129 F5.1 kpc Sep3 Separation, in kpc
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Note (1): classes are divided in 3 categories (section 6.2):
A = Mergers: two similar-size galaxies which are overlapping and
very clearly interacting
B = Highly distorted galaxies, which are interacting as can be judged by
morphological hallmarks as tidal arms, or gross distortions of the
stellar disk
C = galaxies which show some sign of interaction, such as relatively minor
distortions of their disk, or minor tidal features.
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Global Notes:
Note (G1): Sources of optical data:
LT = Liverpool Telescope imaging (instruments: IO:O or RATCam)
DR7 = SDSS DR7
DR8 = SDSS DR8
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Acknowledgements:
Johan Knapen, jhk(at)iac.es
History:
* 29-Sep-2014: on-line data
* 20-Oct-2014: FITS images added (from author)
(End) Johan Knapen [IAC], Patricia Vannier [CDS] 22-Jul-2014